JPS5839784Y2 - electrostatic precipitator - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an electrostatic precipitator, and particularly to the structure of a discharge section.

The present invention relates to a novel electrostatic precipitator having an electrode structure suitable for configuration of an electrostatic precipitator using an external current control and pulse charging method.

Hereinafter, the electrostatic precipitator according to the present invention will be described in detail with reference to the drawings.

FIGS. 1 and 2 are a plan view and a side view of a main part of an electrode section showing an embodiment of an electrostatic precipitator used in the present invention, which is composed of a dust collection section and a discharge section.

The dust collection section has a structure in which dust collection electrodes 1 made of metal flat plates are arranged parallel to each other, and a discharge section is provided on the center line of the dust collection electrodes 1.

This discharge section has a structure in which a plurality of blocks B1 to B4 are arranged in a straight line as shown in FIG. 2, and each discharge block B1 to B4 has a vertical frame 2a,
An electrode support 5 and a third electrode 6 having a discharge electrode 3 and a control electrode 4 fixed therebetween are vertically arranged in parallel at a predetermined distance from each other.

In this case, the discharge electrode 3, control electrode 4, and third electrode 6 are attached as follows.

In other words, as shown in enlarged cross-sectional views and end views of main parts in FIGS. 3 and 4, the vertical frame 2a has a C-shaped cross section (semicircular shape).
The electrode support 5 is made of members 5a and 5b each having a C-shaped (semicircular) cross section for ease of assembly.
are joined facing each other to form a hollow body.

Members 5 a and 5 that constitute this electrode support 5
On the flat part b, a plurality of control electrodes 4 having a circular tip to have a non-discharge structure are planted at equal intervals and extend vertically parallel to the dust collecting electrode 1. are doing.

Further, a discharge electrode support 5C passes through the center of the electrode support constituted by this hollow body, and bolt portions 5d provided at both ends thereof are connected to holes provided in the vertical frames 2a and 2b. The vertical frame is connected to the vertical frame by a nut 9 and a washer 10 along with a power supply bar 8 that penetrates the step-shaped insulating spacer 7 attached to the vertical frame 2a and extends inside the vertical frame 2a in a state electrically independent from the vertical frame 2a. It is collinear with 2 a and 2 b.

Further, between each control electrode 4 of the discharge electrode support rod 5C, a discharge electrode 3 having a needle-shaped tip passes through and is fixed by caulking or the like, and the tip is attached to the electrode support 5. It extends in the direction along the control electrode 4 through the step-shaped insulating spacer 11, and its tip almost coincides with the tip position of the control electrode 4.

Therefore, by tightening the nut 9, the electrode support part 5 has both ends sandwiched between the vertical frames 2a and 2b, and the discharge electrode support rod 5 is placed in the center of the stepped part of the insulating spacer 11.
C will be positioned.

For this reason, the discharge electrode 3 is connected to the power supply bar 8 - discharge electrode support rod 5C.
Power is supplied to the control electrode 4 via the vertical frames 2a, 2b and the electrode support 5.

On the other hand, the third electrode 6 is formed of an elliptical hollow body, and by tightening both ends of two bolts 12 passing through the inside of the body to the vertical frame 2a with nuts 13, the third electrode 6 is vertically It is sandwiched between frames 2a and 2b, and this third electrode 6 is the vertical frame 2a.

By receiving power through 2b, it is brought to the same potential as the control electrode 4.

The discharge sections configured in this way are each made independently as discharge blocks B1 to B4, and then integrated by being arranged side by side and fixed by a horizontal frame 14 as shown in FIG.

In this case, in each of the discharge blocks B] to B4, the arrangement of the electrodes is sequentially shifted in a direction intersecting the direction of the gas flow indicated by arrow A.

In the electrostatic precipitator configured in this way, when a negative high voltage is applied to the discharge electrode 3 via the power supply bar 8 and the discharge electrode support 5C, and a positive high voltage is applied to the dust collection electrode 1, ,
A corona discharge occurs at the tip of the oblique discharge electrode 3, and an electron current flows toward the dust collection electrode 1 while being diffused.

Since the electric field in the space where this current flows has a curved shape due to the electrode support 5 and the third electrode 6,
The current flow range is limited by the shape of this electric field, and the current flow band is the range shown by diagonal lines 14 in FIG.

Within this current flow band 8, current diffusion is restricted, so the current density does not decrease even in areas far from the discharge electrode 3, and a relatively uniform current density can be obtained as a whole. become.

Furthermore, by narrowing the spacing between the discharge electrodes 3, the difference in current density between the discharge electrodes 3 is also reduced, and the current density in the current flow band 14 is almost uniform except for the part very close to the discharge electrodes 3. Ru.

In this case, a control voltage is applied between the discharge electrode 3 and the control electrode 4 and the third electrode 6 via the vertical frames 2a, 2b and the electrode support 5 so that the control electrode 4 and the third electrode 6 are normally negative. Apply it.

When a control voltage is applied in such a state, the electric field near the tip of the discharge electrode 3 is strongly influenced by the control electrode 4 and the third electrode 6.

That is, the lines of electric force caused by the high voltage between the dust collection electrode 1 and the discharge electrode 3 are weakened by the lines of electric force caused by the control electrode 4 and the third electrode 6, The electric field for corona discharge decreases in response to the negative electrode voltage applied to the corona discharge.

In this case, the influence exerted on the electric field that causes corona discharge is given by the potential difference between the discharge electrode 3 and the control electrode 4 and the third electrode 6.
The potential of will control the corona discharge.

FIG. 5 shows the characteristics of the above-mentioned current control,
The corona current Ic is shown when the voltage between the dust collecting electrode 1 and the discharge electrode 3 is set to a constant voltage Vc, and the potential difference between the discharge electrode 3 and the control electrode 4 is varied as Vg.

When the control voltage Vg is set to zero, that is, when the discharge electrode 3 and the control electrode 4 are made to have the same potential, the lines of electric force between the dust collection electrode 1 and the discharge electrode 3 are absorbed by the control electrode 4, and the voltage is lower than when there is no control electrode 4. The corona discharge current also decreases.

Then, Vg is made negative and the potential of the control electrode 4 is changed to the potential of the discharge electrode 3.
When the potential is made more negative than , the current decreases further and finally reaches zero.

That is, the lines of electric force from the dust collecting electrode 1 are canceled out, and the electric field near the tip of the discharge electrode is made lower than the electric field at which discharge is possible.

The control voltage -Vg at this time is proportional to the high voltage Vc between the dust collection electrodes, and as Vc becomes lower, the value of -Vg also becomes lower.

Next, when Vg is made positive and the control electrode potential is made more positive than the discharge electrode potential, the amount of cancellation of the electric lines of force from the dust collection electrode becomes smaller, the electric field of the discharge electrode becomes stronger, and the corona discharge current increases.

Then, when +Vg reaches a certain value, the amount of cancellation disappears and the discharge current becomes almost equal to the case where the control electrode 4 does not exist.

That is, the potential of the control electrode 4 and the potential of the dust collecting electrode 1 become equal.

Then, when +Vg is further increased, the electric field of the discharge electrode 3 becomes stronger, and the discharge current Ic increases accordingly.

However, a part of this discharge current comes to flow into the control electrode 4.

Therefore, the current flowing to the dust collection electrode required to charge the dust is:
As shown by the dotted line in FIG. 5, the amount of increase decreases, and eventually saturates and ceases to increase.

In this way, the electric potential of the control electrode 4 makes it possible to control the discharge current from zero to the normal discharge range, and within this range, no control current flows and no control power is consumed.

Further, by positioning the control electrode 4 close to the discharge electrode 3, similar control can be performed with a smaller control voltage, and accordingly, control can be performed with a small voltage without power.

In this case, since high voltage is still being supplied between the dust collection electrode 1 and the discharge electrode 3, the dust collection capacity is not reduced and the voltage required for the operation of the electrostatic precipitator is maintained. It can satisfy a wide range of conditions.

Therefore, by supplying the control voltage to the control electrode momentarily in a pulsed manner from negative to positive while maintaining a high voltage applied between the dust collection electrode and the discharge electrode, a pulsed current can be obtained. I can do it.

In this case, if the gas flow containing dust flows in the direction shown by arrow A in FIGS. 1 and 2, the dust will encounter the current flow time while traveling through the current flow zone 14'. For example, it is charged according to the electric field strength and current density at that location.

In this case, when the specific resistance of the dust is "LO" Q 7cm, a certain value is set between the current density i/cm2, the current flow time tc, and the discharge time td of the dust layer to prevent the back corona phenomenon from occurring. A relationship is established.

That is, if a normal state is given as the current density, the ratio of td/lc will be about 300.

If the current flow time tc is 5 x 10-' seconds, then td
is 0.15 seconds, meaning that no current will flow for 0.15 seconds.

Therefore, if dust is moving at a flow rate of 1 m/sec, within the current flow zone 14', the dust is moving at a speed of 15 cm.
The current will be encountered for only 5 x 10-' seconds while moving.

Therefore, the length of the current flow band 14' is absolutely 15 c.
It is necessary to provide it so that it exists over a range of m or more.

If the length of the current flow band 14' is short, or if the current density is uneven, the dust will never encounter the current, and as a result, collisional charging will not occur. This results in only weak charging.

Therefore, in order to make the current flow band 14' have a sufficient length and a uniform current density, the electrode structure shown in FIGS. 1 to 4 is required.

However, as shown in FIG. 2, the current flow band 14 does not exist in the portion facing the electrode support 5 and the third electrode 6, and this portion becomes a blank band.

In order to fill this blank zone, multiple blocks B1 to B4 are
are arranged in series, and the electrodes are arranged so that the current flow bands 14 of each block are overlapped and shifted.

In this way, the dust passing through the blank zone of the first block passes through the current flow zone 14 of the second and third blocks, and along with this, most of the dust is given a collision charge. This is something that can be done.

Figure 6 shows an example of a power supply section for an electric precipitator with the above-mentioned electrode structure.The high-voltage power supply section does not need to use a special circuit, but can be done by using a commonly used single-phase full-wave rectifier circuit. good.

That is, as shown in FIG. 6, the commercial power supplied to the power input terminal 20 is boosted to a necessary voltage by the high voltage transformer 21. As shown in FIG.

The high-voltage output of the high-voltage transformer 21 is converted into direct current in a single-phase full-wave semiconductor rectifier 22, and a negative high voltage is supplied to the discharge electrode 3, and a positive high voltage is supplied to the dust collection electrode 1. is supplied.

Further, the control power supplied to the control electrode 4 and the third electrode 6 is constituted by a bias power supply and a control pulse.

That is, the bias power supply always supplies a negative voltage to the control electrode 3 to prevent corona discharge from occurring in the discharge electrode 3.

For this purpose, the circuit boosts the commercial power supply to the necessary bias voltage in a transformer 23, and converts the boosted output into a DC voltage in a single-phase full-wave semiconductor rectifier 24.

This rectified output is then connected to a resistor 25 and a capacitor 2.
6 removes ripples.

This is because when a high voltage is applied between the dust collecting electrode 1 and the discharge electrode 3, a high voltage with less ripple is supplied to the discharge electrode 3 due to the capacitance of the electrode. This is because the bias voltage applied to the control electrode 4 also needs to have less ripple.

27 is a dead load resistor, which includes a resistor 25 and a capacitor 26.
The diode 28 is provided to reduce the cut-off phenomenon caused by the transformer 23 and the semiconductor rectifier 2.
It is provided to protect 4.

The bias power supply generated in this manner has its positive terminal connected to the high voltage, and its negative terminal connected to the control electrode 4.

In this case, the control pulse voltage is provided by a pulse transformer 29 connected in series with the bias power supply.

In addition, 30. It is a load resistance for stably operating the pulse transformer 29.

On the other hand, since the control circuit 31 is connected to a high voltage circuit,
The secondary windings of transformer 23 and pulse transformer 29 must have dielectric strength sufficient to withstand high voltages.

This control circuit 31 is a device that generates control pulses, and is spaced at predetermined intervals and has a width of 5 x 10-
By supplying a pulse current of 4 seconds or less to the pulse transformer 29, the necessary voltage is supplied to the control electrode 4.

As explained above, the electrostatic precipitator according to the present invention has excellent effects in that the discharge section is suitable for current control and its assembly is extremely easy.

[Brief explanation of the drawing]

Figures 1 and 2 are a plan view and side view of essential parts of an embodiment of the electrostatic precipitator according to the present invention, and Figures 3 and 4 are specific examples of the discharge section shown in Figures 1 and 2. Main part sectional view shown, No. 5
The figure is a control characteristic diagram of the control electrode shown in FIG. 1, and FIG. 6 is a circuit diagram showing an example of a power supply section. 1... Dust collection electrode, 2 a, 2 b...
・Vertical frame, 3...discharge electrode, 4...control electrode, 5...electrode support, 5a, 5b・
... Member, 5C ... Discharge electrode support, 5d
...... Bolt part, 6... Third electrode, 7.
...Insulation spacer, 8...Power supply bar, 9
...Natsuto, 10...Washer, 11
...Insulating spacer.

Claims (2)

[Scope of utility model registration request] (1) In an electrostatic precipitator including a discharge part and a dust collection part which are arranged opposite to each other via a passage of gas containing dust, the discharge part is connected to a cylindrical electrode support and the electrode a plurality of control electrodes having a non-discharge shape protruding from the side of the support;
A discharge electrode support that penetrates the inside of the electrode support in an electrically independent state, and a tip that penetrates between each control electrode in an electrically independent state from the side of the discharge electrode support. An electrostatic precipitator comprising a needle-shaped discharge electrode. (2) The electrode support body is composed of semicircular first and second members divided along the tube axis direction, and the first and second members provided with the control electrode are implanted with the discharge electrode. 2. The electrostatic precipitator according to claim 1, wherein the electrostatic precipitator is constructed by assembling discharge electrode supports from both sides and integrating them into a circular cross-sectional shape.